Fluoride Action Network

Adsorption of fluoride from aqueous solution by fly ash cenospheres modified with paper mill lime mud: Experimental and modeling

Source: Ecotoxicology and Environmental Safety 180:366-373. | September 10th, 2019 | Ye C, Yan B, Ji X, Liao B, Gong R, Pei X, Liu G.
Location: International
Industry type: Water Treatment

Highlights

  • A low-cost fly ash cenospheres modified with paper mill lime mud adsorbent was prepared.
  • Response surface methodology was employed to research the effects on fluoride removal.
  • Nonelectrostatic model-Generalized composite approach had successfully described and predicted the adsorption process.
  • —SF and —SOHF formed in the removal of fluoride via the ligand exchange and surface complexation.

Fluoride removal from aqueous solution by adsorption using fly ash cenospheres (FAC) modified with paper mill lime mud (LM) as composite adsorbent had been investigated. The characterization of FAC and composite adsorbent were analyzed by Scanning electron spectroscope (SEM), Energy dispersive spectrometer (EDS), Brunauer emmett teller (BET) and Fourier transform infrared (FTIR), which demonstrated that the porous structure of composite adsorbent was obtained after surface modification. Adsorption of fluoride on modified fly ash cenospheres was fitted with pseudo-second-order model and Langmuir model. Response surface methodology (RSM) was employed to investigate the effects of F concentration, pH, adsorbent dosage and temperature on the removal efficiency. Analysis of variance (ANOVA) was used to test the adequacy of the mathematical models. The Nonelectrostatic model of modified fly ash cenospheres adsorbing fluoride was built through the Generalized composite method, indicating that two inner-spherical complexes, —SF and —SOHF, were formed in the adsorption process by means of the ligand exchange and surface complexation. Optimization of the adsorption conditions enabled the realization of the practical needs for fluoride contaminated water.

Graphical abstract